Formation-testing tool for obtaining multiple measurements and fluid samples

ABSTRACT

In the representative embodiment of the new and improved wireline formation-testing apparatus disclosed herein, pressureresponsive fluid-admitting means and tool-anchoring means are cooperatively arranged on a tool body for selectively anchoring the tool in position in a well bore for obtaining at least one measurement or fluid sample from a sub-surface earth formation. The new and improved tool further includes a selectively-operable hydraulic pump which is coupled by a plurality of selectivelyoperable hydraulic valves to the pressure-responsive means as well as to one or more pressure-responsive flow-control valves. By arranging each of the hydraulic control valves to operate only at selected hydraulic pressures, the new and improved formationtesting tool is sequentially operated as required to obtain selected measurements and, if desired, one or more samples of the formation fluids from one or more formation intervals before removing the tool from the well bore.

United States Patent 1191 Urbanosky 1451 Dec. 25, 1973 FORMATION-TESTING TOOL FOR OBTAINING MULTIPLE MEASUREMENTS AND FLUID SAMPLES US. Cl. 73/152, 166/100 E21b 49/00 Field of Search 73/151, 152, 421 R, 73/155; 166/100 Primary Examiner-Jerry W. Myracle AttorneyErnest R. Archambeau, Jr. et al.

[57 ABSTRACT In the representative embodiment of the new and improved wireline formation-testing apparatus disclosed herein, pressure-responsive fluid-admitting means and tool-anchoring means are cooperatively arranged on a tool body for selectively anchoring the tool in position in a well bore for obtaining at least one measurement or fluid sample from a sub-surface earth formation. The new and improved tool further includes a selectively-operable hydraulic pump which is coupled by a plurality of selectively-operable hydraulic valves to the pressure-responsive means as well as to one or more pressure-responsive flow-control valves. By ar- [56] References Cited ranging each of the hydraulic control valves to operate UNITED STATES PATENTS only at selected hydraulic pressures, the new and im- 3,011,554 12 1961 Desbrandes et a1. 166 100 Proved tool sequennauy operate? 3,352,361 11/1967 Urbanosky 166/100 as feq'llred Obtaln Selected measurements 3,335,364 19 3 whine mm desired, one or more samples of the formation fluids 3,530,933 9/1970 Whitten 166/100 from one or more formation intervals before removing 3,565,169 2/1971 Bell 166/100 the tool from the well bore.

3,577,781 5/1971 Lebourg 73/152 3,653,436 4 1972 Anderson et al. 166 40 Chums, 13 Drama Flsllres 1 2 ELECTRICAL 25 M ICONTROLS 7 T 2 c" 7/ 11a M ;"-"/Z4a;1 -11]5g 7260 12m F g 7 5182a l 1.1. 7 L p u 9 ,1 125 v 5:351 123 1 110 g m I27 2 r? I" W V V iii ,2] J "9 J I PATENIEUuEc 25 I975 SREEI 01 0F 10 POWER SUPPLY F/Gl CHI/6.6)

B(F/G.5)

TIME

PATENTED DEC 2 5 I975 saw on 0; 1,0

PATENTEU DEC 25 I975 SHEET 05 0F 10 PAIENTEUUEBIZS m 3.? 80.575 saw us or 10 FIG. 5A 1 if k l 102 I FROM 30 1 FIG. 6B)

PATENTEUUEEZSIQIS 3.780.575

SHEEI 070F10 PATENTEUBECZS m5 3.780.575

sum uaur 10 PATENTED [151125 1915 3. 780.575

sum mm 10 1 FORMATION-TESTING TOOL FOR OBTAINING MULTIPLE MEASUREMENTS AND FLUID SAMPLES l-leretofore, the typical wireline formation testers (such as the tool disclosed in U.S. Pat. No. 3,01 1,554) which have been most successful in commercial service have been limited to attempting only a single test of one selected formation interval. Those skilled in the art will appreciate that once one of these typical tools is positioned in a well bore and a sampling or testing operation is initiated, the tool cannot be again operated without first removing it from the well bore and reconditioning various tool components for another run. Thus, even should it be quickly realized that a particular sampling or testing operation already underway will probably be unsuccessful, the operator has no choice except to discontinue the operation and then return the tool to the surface. This obviously results in a needless loss of time and expense which would usually be avoided if another attempt could be made without having to remove the tool from the well bore.

To counter this significant limitation, more-modern tools such as shown in U.S. Pat. No. 3,385,364 have been used with some success. As disclosed there, these formation testers typically include two or more selfcontained testing units which are tamdemly coupled to one another and cooperatively arranged for independent operation. Although tools such as these have been commercially employed, it has been found that their overall weight and length make it difficult to use such tools in many situations.

Various proposals have, of course, been advanced heretofore for providing formation-testing tools which are presumably capable of conducting more than one testing or sampling operation during a single run. Most of these proposed tools have, however, employed such unduly complicated arrays of solenoid-actuated valves and elaborate downhole controls that it is doubtful that these fanciful tools would be suited for reliable commercial operation under the adverse well bore conditions typically encountered today.

Another problem which has heretofore prevented the production of a commercially successful repetitivelyoperable formation-testing tool has been in providing a suitable arrangement for reliably establishing fluid or pressure communication with incompetent or unconsolidated earth formations. Although the several new and improved testing tools respectively shown in U.S. Pat. No. 3,352,361, U.S. Pat. No. 3,530,933, U.S. Pat. No. 3,565,169 and U.S. Pat. No. 3,653,436 are especially arranged for testing unconsolidated formations, for one reason or another these tools are not adapted for performing more than one testing operation during a single run in a given well bore.

One of the better prior-art repetitively-operable testing tools which is suited for commercial operations is shown in H6. 2 of U.S. Pat. No. 3,577,781. As disclosed there, this new and improved tool employs a straight-forward control system having only a single solenoid-actuated valve and a selectively-reversible hydraulic pump. it will be recognized, however, that this tool is not arranged for collecting a fluid sample which can be returned to the surface for examination. Moreover, since the fluid-admission port in this tool is permanently open, a tool such as this is not intended for operation where the formation being investigated is relatively unconsolidated.

Accordingly, it is an object of the present invention to provide new and improved well bore apparatus for reliably obtaining multiple measurements of one or more fluid or formation characteristics as well as selectively collecting one or more samples of formation fluids, if desired, without regard to the nature or competency of the formations being tested.

This and other objects of the present invention are attained by providing a formation tester with selective ly-operable means arranged for releasably anchoring the tool in a well bore as well as for establishing isolated communication with an earth formation while limiting or preventing the admission of loose formation materials and also including selectively-operable means for obtaining at least measurements indicative of one or more characteristics of the earth formation or connate fluids contained therein. To selectively operate the tool for one or more testing cycles, each of the several selectively-operable means as well as various flow control valves arranged in the tool are cooperatively coupled to a selectively-operable hydraulic pump by way of a control system including a plurality of hydraulic control valves respectively adapted to operate at different predetermined hydraulic pressures. In this manner, by simply starting the hydraulic pump, as the output pressure of the pump rises, each of the several hydraulic control valves will be successively operated in a predetermined sequence as required for carrying the tool through a selected operating cycle.

The novel features of the present invention are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may be best understood by way of the following description of exemplary apparatus employing the principles of the invention as illustrated in the accompanying drawings, in which:

FIG. 1 depicts the surface and downhold portions of a preferred embodiment of new and improved formation-testing apparatus incorporating the principles of the present invention;

FIGS. 2A and 23 together show a somewhatschematic representation of the formation-testing tool illustrated in FIG. 1 as the tool will appear in its initial operating position;

FIG. 3 is a representative performance curve graphically depicting the operation of the new and improved formation-testing tool of the present invention as it selectively conducts a typical testing and sampling operation;

FIGS. 4-7 respectively depict the successive positions of various components of the new and improved tool shown in FIGS. 2A and2B during the course of a typical testing and sampling operation;

FIG. 8 is similar to FIG. 3 but graphically illustrates the operation of the formation-testing tool as it selectively returns to its initial operating position following a complete testing and sampling operation; and

FIGS. 9-11 respectively show the successive positions of the several components of the new and improved formation-testing tool as the tool is returned to its initial operating position.

Turning now to FIG. 1, a preferred embodiment of a new and improved formation-testing tool 20 incorporating the principles of the present invention is shown as it will appear during the course of a typical measuring and sampling operation in a well bore such as a borehole 21 penetrating one or more earth formations as at 22 and 23. As illustrated, the tool is suspended in the borehole 21 from the lower end of a typical multiconductor cable 24 that is spooled in the usual fashion on a suitable winch (not shown) at the surface and coupled to the surface portion of a new and improved toolcontrol system 25 as well as typical recording and indicating apparatus 26 and a power supply 27. In its preferred embodiment, the tool 20 includes an elongated body 28 which encloses the downhole portion of the new and improved control system 25 and carries selectively-extendible tool-anchoring means 29 and new and improved fluid-admitting means 30 arranged on opposite sides of the body as well as one or more tandemly-coupled fluid-collecting chambers 31 and 32.

As will be subsequently explained in greater detail, the new and improved formation-testing tool 20 and the control system 25 are cooperatively arranged so that, upon command from the surface, the tool can be selectively placed in any one or more of five selected operating positions. As will be subsequently described, the control system 25 will function to either successively place the tool 20 in one or more of these positions or else cycle the tool between selected ones of these operating positions. These five operating positions will be described later by reference to various ones of the several drawings depicting the versatility of the unique tool-control system 25 which functions to operate the tool 20 for achieving the objects of the present invention by selectively moving suitable control switches, as schematically represented at 33 and 34, included in the surface portion of the system to various switching positions, as at -40, so as to selectively apply power to different conductors 41-48 in the cable 24.

Turning now to FlGS. 2A and 2B, the entire downhole portion of the control system 25 as well as the tool'anchoring means 29, the fluid-admitting means 30 and the fluid-collecting chambers 31 and 32 of the tool 20 are schematically illustrated with their several elements or components depicted as they will respectively be arranged when the new and improved tool is fully retracted and the switches 33 and 34 are in their first or off" operating positions 35. in the preferred embodiment of the selectively-extendible tool-anchoring means 29 schematically illustrated in FIG. 2A, an upright wall-engaging anchor member 50 is coupled in a typical fashion to a longitudinally-spaced pair of rearwardly-movable piston actuators 51 and 52 of a typical design mounted transversely on the tool body 28. As will be subsequently explained, the lateral extension and retraction of the wall-engaging member 50 in relation to the rear of the tool body 28 is controlled by the control system 25 which is operatively arranged to selectively admit and discharge a pressured hydraulic fluid to and from the piston actuators 51 and 52.

The fluid-admitting means 30 employed with the preferred embodiment of the new and improved tool 20 are cooperatively arranged for sealing-off or isolating selected portions of the wall of the borehole 21; and, once a selected portion of the borehole wall is packedoff or isolated from the well bore fluids, establishing pressure of fluid communication with the adjacent earth formations. As depicted in FIG. 2A, the fluidadmitting means 30 preferably include an annular elastomeric sealing pad 53 mounted on the forward face of an upright support member or plate 54 that is coupled to a longitudinally-spaced pair of forwardly-movable piston actuators 55 and 56 respectively arranged transversely on the tool body 28 for moving the sealing pad laterally in relation to the forward side of the tool body. Accordingly, as the new and improved control system 25 selectively supplies a pressured hydraulic fluid to the piston actuators 55 and 56, the sealing pad 53 will be moved laterally between a retracted position adjacent to the forward side of the tool body 28 and an advanced or forwardly-extended position.

By arranging the annular sealing member 53 on the opposite side of the tool body 28 from the wallengaging member 50, the lateral extension of these two members will, of course, be effective for urging the sealing pad into sealing engagement with the adjacent wall of the borehole 21 and anchoring the tool 20 each time the piston actuators 51, 52, 55 and 56 are extended. It will, however, be appreciated that the wallengagirlg member as well as its piston actuators 51 and 52 would not be needed if the effective stroke of the piston actuators and 56 would be sufficient for assuring that the sealing member 53 can be extended into firm sealing engagement with one wall of the borehole 21 with the rear of the tool body 28 securely anchored against the opposite wall of the borehole. Conversely, the piston actuators 55 and 56 could be similarly omitted where the extension of the wall-engaging member 50 alone would be effective for moving the other side of the tool body 28 forwardly toward one wall of the borehole 21 so as to place the sealing pad 53 into firm sealing engagement therewith. However, in the preferred embodiment ofthe formation-testing tool 20, both the tool-anchoring means 29 and the fluidadmitting means 30 are made selectively extendible to enable the tool to be operated in boreholes of substantial diameter. This preferred design of the tool 20, of course, resulsts in the overall stroke of the piston actuators 51 and 52 and the piston actuators 55 and 56 being kept to a minimum so as to reduce the overall diameter of the tool body 28.

To conduct connate fluids into the new and improved tool 20, the fluid-admitting means 30 further include an enlarged tubular member 57 having an open forward portion coaxially disposed within the sealing pad 53 and a closed rear portion which is slidably mounted within a larger tubular member 58 secured to the rear face of the plate 54 and extended rearwardly therefrom. By arranging the nose of the tubular fluidadmitting member 57 to normally protrude a short distance ahead of the forward face of the sealing pad 53, extension of the fluid-admitting means 30 will engage the forward end of the fluid-admitting member with the adjacent surface of the wall of the borehole 21 as the annular sealing pad is also forced thereagainst for isolating that portion of the borehole wall as well as the nose of the fluid-admitting member from the well bore fluids. To selectively move the tubular fluid-admitting member 57 in relation to the enlarged outer member 58, the smaller tubular member is slidably disposed within the outer tubular member and fluidly sealed in relation thereto as by sealing members 59 and 60 on inwardly-enlarged end portions 61 and 62 of the outer member and a sealing member 63 on an enlargeddiameter intermediate portion 64 of the inner member.

Accordingly, it will be appreciated that by virtue of the sealing members 59, 60 and 63, enclosed piston chambers 65 and 66 are defined within the outer tubular member 58 and on opposite sides of the outwardlyenlarged portion 64 of the inner tubular member 57 which, of course, functions as a piston member. Thus, by increasing the hydraulic pressure in the rearward chamber 65, the fluid-admitting member 57 will be moved forwardly in relation to the outer tubular member 58 as well as to the sealing pad 53. Conversely, upon the application of an increased hydraulic pressure to the forward piston chamber 66, the fluid-admitting member 57 will be retracted in relation to the outer member 58 and the sealing pad 53.

Pressure or fluid communication with the fluidadmitting means 30 is controlled by means such as a generally-cylindrical valve member 67 which is coaxially disposed within the fluid-admitting member 57 and cooperatively arranged for axial movement therein between a retracted or open position and the illustrated advanced or closed position where the enlarged forward end 68 of the valve member is substantially, if not altogether, sealingly engaged with the forwardmost interior portion of the fluid-admitting member. To support the valve member 67, the rearward portion of the valve member is axially hollowed, as at 69, and coaxially disposed over a tubular member 70 projecting forwardly from the transverse wall closing the rear end of the fluid-admitting member 57. The axial bore 69 is reduced and extended forwardly along the valve member 67 to a termination with one or more transverse fluid passages 71 in the forward portion of the valve member just behind its enlarged head 68.

To provide piston means for selectively moving the valve member 67 in relation to the fluid-admitting member 57, the rearward portion of the valve member is enlarged, as at 72, and outer and inner sealing members 73 and 74 are coaxially disposed thereon and respectively sealingly engaged with the interior of the fluid-admitting member and the exterior of the forwardly-extending tubular member 70. A sealing member 75 mounted around the intermediate portion of the valve member 67 and sealingly engaged with the interior wall of the adjacent portion of the fluid-admitting member 57 fluidly seals the valve member in relation to the fluid-admitting member. Accordingly, it will be appreciated that by increasing the hydraulic pressure in the enlarged piston chamber 76 defined to the rear of the enlarged valve portion 72 which serves as a piston member, the valve member 67 will be moved forwardly in relation to the fluid-admitting member 57. Conversely, upon application of an increased hydraulic pressure to the forward piston chamber 77 defined between the sealing members 73 and 75, the valve member 67 will be moved rearwardly along the forwardlyprojecting tubular member 70 so as to retract the valve member in relation to the fluid-admitting member 57.

Those skilled in the art will, of course, appreciate that many earth formations, as at 22, are relatively unconsolidated and are, therefore, readily eroded by the withdrawal of connate fluids. Thus, to prevent any significant erosion of such unconsolidated formation materials, the fluid-admitting member 57 is arranged to define an internal annular space 78 and a flow passage 79 in the forward portion of the fluid-admitting member and a tubular screen 80 of suitable fineness is coaxially mounted around the annular space. In this manner, when the valve member 67 is retracted, formation fluids will be compelled to pass through the exposed forward portion of the screen ahead of the enlarged head 68, into the annular space 78, and then through the fluid passage 79 into the fluid passages 71 and 69. Thus, as the valve member 67 is retracted, should loose or unconsolidated formation materials be eroded from a formation as connate fluids are withdrawn therefrom, the materials will be stopped by the exposed portion of the screen 80 ahead of the enlarged head 68 of the valve member thereby quickly forming a permeable barrier to prevent the continued erosion of loose formation materials once the valve member halts.

A sample or flow line 81 is cooperatively arranged in the formation-testing tool 20 and has one end coupled, as by a flexible conduit 82, to the fluid-admitting means and its other end terminated in a pair of branch conduits 83 and 84 respectively coupled to the fluidcollecting chambers 31 and 32. To control the communication between the sample-admitting means 30 and the fluid-collecting chambers 31 and 32, normallyclosed flow-control valves 85-87 of a similar or identical design are arranged respectively in the flow line 81 and in the branch conduits 83 and 84 leading to the sample chambers. For rreasons which will subsequently be described in greater detail, a normally-open control valve 88 which is similar to the normally-closed control valves 85-87 is cooperatively arranged in a branch conduit 89 for selectively controlling communication between the well bore fluids exterior of the tool 20 and the upper portion of the flow line 81 extending between the flow-line control valve 85 and the fluid-admitting means 30.

As illustrated, the flow-line control valve 85 (as well as each of the chamber control valves 86 and 87) is comprised of an elongated body 90 having an enlarged piston cylinder 91 cooperatively arranged for carrying an actuating piston 92 which is normally biased to a lower position by a spring 93 of a predetermined strength. A valve member 94 coupled to the piston member 92 is cooperatively arranged for blocking fluid communication between inlet and outlet ports 95 and 96 so long as the piston is in its lower position. To control the operation of the valve 85, ports 97 and 98 are provided for the admission and discharge of hydraulic fluid into the cylinder 91 above and below the actuating piston 92. The valve 88 is similar to the valves 85-87 except that a spring 99 of selected strength normally biases the valve member 100 to an open position.

As shown in FIGS. 2A-2B, a branch conduit 101 is coupled to the flow line 81 at a convenient location between the sample chamber control valves 86 and 87 and the flow-line control valve 85, with this branch conduit being terminated by selectively-operable pressure-reduction means 102. In its preferred form, the pressure-reduction means 102 include a body 103 having an enlarged piston cylinder. 104 in which an actuating piston 105 is operatively mounted for carrying a reduced-diameter displacement piston 106 between selected upper and lower positions within a reduced chamber 107 of a predetermined volume. To control the movements of the displacement piston 106, hydraulic ports 108 and 109 are provided for admitting and exhausting hydraulic fluid into and from the isolated portions of the larger actuating cylinder 104 on opposite sides of the actuating piston 105. Accordingly, it will be appreciated that upon movement of the displacement piston 106 from its lower position as illustrated in FIG. 2A to an elevated or upper position, the

combined volume of whatever fluids that are then contained in the branch conduit 101 as well as that portion of the flow line 81 between the flow-line control valve 85 and the sample chamber control valves 86 and 87 will be correspondingly increased. The significance of the substantial reduction in pressure caused by this selective increase in volume will be subsequently explained.

As best seen in FIG. 2A, the preferred embodiment of the control system 25 further includes a pump 110 that is coupled to a driving motor 111 and cooperatively arranged for pumping a suitable hydraulic fluid such as oil or the like from a reservoir 112 into a discharge or outlet line 113. Since the tool 20 is to be operated in well bores, as at 21, which typically contain dirty and usually corrosive fluids, the reservoir 112 is preferably arranged to totally immerse the pump 110 and the motor 111 in the clean hydraulic fluid. Inasmuch as the formation-testing tool 20 must operate at depths where the hydrostatic pressure of the surrounding well bore fluids can be as high as l520,000-psig, the reservoir 112 is provided with an inlet 114 for well bore fluids and an isolating piston 115 is movably arranged in the reservoir for maintaining the hydraulic fluid contained therein at a pressure about equal to the hydrostatic pressure at whatever depth the tool is then situated. Biasing means, such as a spring 116 acting on the piston 115, are provided for maintaining the pressure of the hydraulic fluid in the reservoir 112 at an increased level slightly above the well bore hydrostatic pressure so as to at least minimize the influx of well bore fluids into the reservoir. It will, of course, be recognized that in addition to isolating the hydraulic fluid in the reservoir 112, the piston 115 will also be free to move as required to accommodate volumetric changes in the hydraulic fluid which may occur under different well bore conditions. One or more inlets, as at 117 and 118, are provided for returning hydraulic fluid from the control systems 25 to the reservoir 112 during the operation of the tool 20.

The fluid outlet line 113 is divided into two major branch lines which are respectively designated as the "set" line 119 and the retract line 120. As will be subsequently described, the control system 25 is arranged to selectively direct hydraulic fluid at selected pressures and times through the set" and retract" lines 119 and 120 to one or more of the several components of the formation-testing tool 20 as required to operate the tool during the course of a testing or sampling operation. The preferred operating sequences will be discussed later.

To control the admission of hydraulic fluid to the set and retract" lines 119 and 120, the new and improved control system 25 further includes selectivelyoperable valve means such as a pair of normally-closed solenoid-actuated valves 121 and 122 which are cooperatively arranged to selectively admit hydraulic fluid to the two lines as the control switch 33 at the surface is selectively positioned. For reasons which will subsequently be explained, a typical check valve 123 is arranged in the set line 119 downstream of the control valve 121 for preventing the reverse flow of the hydraulic fluid whenever the pressure in the set" line is greater than that then existing in the fluid outlet line 113. Control devices, such as typical pressure switches 124-126, are cooperatively arranged in the set" and retract" lines 119 and 120 for selectively discontinuing operation of the pump whenever the pressure of the hydraulic fluid in either of these lines reaches a desired maximum operating pressure and then restarting the pump whenever the pressure drops below this value so as to maintain the line pressure within a selected operating range.

it will, of course, be recognized that since it is preferred that the pump 110 be a positive-displacement type to achieve a rapid predictable rise in the operating pressures in the set and retract lines 119 and 120 in a minimum length of time, the control system 25 should also provide for temporarily opening the outlet line 1 13 until the motor 111 has reached its rated operating speed. Accordingly, the control system 25 is cooperatively arranged so that each time the pump 110 is to be started, the control valve 122 (if it is not already open) as well as a third normally-closed solenoidactuated valve 127 will be temporarily opened to bypass hydraulic fluid directly from the output line 113 to the reservoir 112 by way of the return line 117. Once the motor 111 has reached operating speed, the bypass valve 127 will, of course, be reclosed and either the set line control valve 121 or the retract line control valve 122 will be selectively opened as required for that particular operational phase of the tool 20. it should be noted that during those times that the retract line control valve 122 and the fluid-bypass valve 127 are opened to allow the motor 111 to reach its operating speed, the check valve 123 will function to pre vent the reverse flow of hydraulic fluid from the set" line 119 when the set line control valve 121 is open.

Accordingly, it will be appreciated that the control system 25 cooperates for selectively supplying pressured hydraulic fluid to the set and retract lines 119 and 120. Since the pressure switches 124 and 125 respectively. function only to limit the pressures in the set and retract lines to a selected maximum pressure range commensurate with the rating of the pump 110, the new and improved control system 25 is further arranged to cooperatively regulate the pressure of the hydraulic fluid which is being supplied at various times to selected portions of the system. Although this regulation can be accomplished in different manners, it is preferred to employ a number of pressure-actuated control valves such as shown schematically at 128-131 in FIGS. 2A and 2B. As shown in FIG. 2A, the control valve 128, for example, includes a valve body 132 having a valve seat 133 coaxially arranged therein between inlet and outlet fluid ports 134 and 135. The upper portion of the valve body 132 is enlarged to provide a piston cylinder 136 carrying an actuating piston 137 in coincidental alignment with the valve seat 133. Biasing means, such as a spring 138 of a predetermined strength, are arranged for normally urging the actuating piston 137 toward the valve seat 133 and a control port 139 is provided for admitting hydraulic fluid into the cylinder 136 at a sufficient pressure to overcome the force of this spring whenever the piston is to be selectively moved away from the valve seat. Since the control system 25 operates at pressures no less than the hydrostatic pressure of the well bore fluids, a relief port 140 is provided in the valve body 132 for communicating the space in the cylinder 136 above the actuating piston 137 with the reservoir 112. A valve member 141 complementally shaped for seating engagement with the valve seat 133 is cooperatively coupled to the actuating piston 137 as by an upright stem 142 which is slidably disposed in an axial bore 143 in the piston. A spring 144 of selected strength is disposed in the axial bore 143 for normally urging the valve member 141 into seating engagement with the valve seat 133.

Accordingly, in its operating position depicted in FIG. 2A, the control valve 128 (as well as the valve 129) will simply function as a normally-closed check valve. That is to say, in this operating position, hydraulic fluid can flow only in a reverse direction from the outlet 135 to the inlet 134 whenever the pressure at the outlet is sufficiently greater than the inlet pressure to elevate the valve member 141 from the valve seat 133 against the predetermined closing force imposed by the spring 144. On the other hand, when sufficient fluid pressure is applied to the control port 139 for elevating the actuating piston 137, opposed shoulders, as at 145, on the stem 142 and the piston will engage for elevating the valve member 141 from the valve seat 133.

As shown in FIGS. 2A and 2B, it will be appreciated that the control valve 130 (as well as the valve 131) is similar to the control valve 128 except that in the firstmentioned control valve, the valve member 146 is preferably rigidly coupled to its associated actuating piston 147. Thus, the control valve-130 (as well as the valve 131) has no alternate checking action allowing reverse flow and is simply a normally-closed pressure-actuated valve for selectively controlling fluid communication between its inlet and outlet ports 148 and 149. Hereagain, the hydraulic pressure at which the control valve 130 (as well as the valve 131) is to selectively open is governed by the predetermined strength of the spring 150 normally biasing the valve member 146 to its closed position.

The set line 119 downstream of the check valve 123 is comprised of a low-pressure section 151 having one branch 152 coupled to the fluid inlet of the control valve 130 and another branch 153 which is coupled to the fluid inlet of the control valve 128 to selectively supply hydraulic fluid to a high-pressure section 154 of the set line which is itself terminated at the fluid inlet of the control valve 131. To regulate the supply of hydraulic fluid from the low-pressure section 151 to the high-pressure section 154 of the set" line 119, a pressure-communicating line 155 is coupled between the low-pressure section and the control port of the control valve 128. Accordingly, so long as the pressure of the hydraulic fluid in the low-pressure section of the set line 119 remains below the predetermined actuating pressure required to open the control valve 128, the high-pressure section 154 will be isolated from the lowpressure section 151. Conversely, once the hydraulic pressure in the low-pressure line 151 reaches the predetermined actuating pressure of the valve 128, the control valve will open to admit the hydraulic fluid into the high-pressure line 154.

The control valves 130 and 131 are respectively arranged to selectively communicate the low-pressure and high-pressure sections 151 and 154 of the set line 119 with the fluid reservoir 112. To accomplish this, the control ports of the two control valves 130 and 131 are each connected to the retract line 120 as by suitable pressure-communicating lines 156 and 157. Thus, whenever the pressure in the retract line 120 reaches their respective predetermined actuating levels, the control valves 130 and 131 will be respectively opened to selectively communicate the two sections 151 and 154 of the set line'119 with the reservoir 112 by way of the return line 117 coupled to the respective fluid outlets of the two control valves.

As previously mentioned, in FIGS. 2A-2B the formation-testing tool 20 and the sub-surface portion of the control system 25 are depicted as their several components will appear when the tool is in its initial or retracted"operating position. At this point, the wallengaging member 50 and the sealing pad 53 are respectively retracted against the tool body 28 to facilitate passage of the tool 20 into the borehole 21. To prepare the tool 20 for lowering into the borehole 21, the switches 33 and 34 are moved to their second or initialization positions 36. At this point, the hydraulic pump 110 is started to raise the pressure in the retract line 120 to maximum pressure to be certain that the pad 53 and the wall-engaging member 50 are fully retracted. As previously mentioned, the control valves 122 and 127 will be momentarily opened when the pump 110 is started until the pump motor 111 has reached its operating speed. At this time also, the control valve 88 is open and that portion of the flow line 81 between the closed flow-line control valve 85 and the fluid-admitting means 30 will be filled with well bore fluids at the hydrostatic pressure at the depths at which the tool 20 is then situated.

In operating the new and improved tool 20, it is necessary only to selectively position the control switches 33 and 34 (FIG. 1) at one or more of their several switching positions 35-40. Thus, when the tool 20 is at a selected operating depth, the switches 33 and 34 are advanced to their third positions 37. By this time the pump will have been halted so that moving of the switch 33 to its set position 37 will restart the pump for developing an increased pressure in the set line. Hereagain, the valves 122 and 127 will be momentarily opened to allow the motor 111 to reach its full speed before the control system 25 begins to function to initiate setting of the tool 20. Then, as schematically represented by the exemplary system performance curve 158 in FIG. 3, once the pump 110 has reached its rated operating speed, the hydraulic pressure in the output line 113 will rapidly rise to its selected maximum operating pressure as determined by the maximum or off setting of the pressure switch 124. As the pressure progressively rises, the control system 25 will successively function at selected intermediate pressure levels respectively designated by the letters A-D in FIG. 3.

Turning now to FIG. 4, selected portions of the control system 25 and various components of the formation-testing tool 20 are schematically represented to illustrate the operation of the tool at about the time that the pressure in the hydraulic output line 113 reaches its lowestmost operating pressure as designated at A in FIG. 3. To facilitate an understanding of the operation of the tool 20 and the control system 25, only those components which are then operating are shown in FIG. 4.

At this time, since the control switch 33 (FIG. 1) is in its third position 37, the solenoid valves 121 and 127 will be open; and, since the hydraulic pressure in the set line 119 has not yet reached the upper pressure limit as determined by the pressure switch 124, the pump motor 111 will be operating. Since the control valve 128 (not shown in FIG. 4) is closed, the highpressure section 154 of the set line 119 will still be isolated from the low-pressure section 151. Simultaneously, the hydraulic fluid contained in the forward pressure chambers of the piston actuators 51, 52, and 56 will be displaced (as shown by the arrows as at 159) to the "retract" line 120 and returned to the reservoir 112 by way of the open solenoid valve 127. These actions will, of course, cause the wall-engaging member 50 as well as the sealing pad 53 to be respectively extended in opposite lateral directions until each has moved into firm engagement with the opposite sides of the borehole 21.

It will be noticed in FIG. 4 that hydraulic fluid will be admitted by way of branch hydraulic lines 160 and 161 to the annular chamber to the rear of the enlargeddiameter portion 64 of the fluid-admitting member 57. At the same time, hydraulic fluid from the piston cham ber 66 ahead of the enlargeddiameter portion 64 will be discharged by way of branch hydraulic lines 162 and 163 to the retract" line 120 to progressively move the fluid-admitting member 57 forwardly in relation to the sealing member 53 until the nose of the fluid-admitting member engages the wall of the borehole 21 and then halts. The sealing pad 53 is then urged forwardly in relation to the now-halted tubular member 57 until the pad sealingly engages the borehole wall for packing-off or isolating the isolated wall portion from the well bore fluids.

It should also be noted that although the pressured hydraulic fluid is also admitted at this time into the forward piston chamber 77 between the sealing members 73 and 75 on the valve member 67, the valve member is temporarily prevented from moving rearwardly in relation to the inner and outer tubular members 57 and 58 inasmuch as the control valve 129 (not shown in (FIG. 4) is still closed thereby temporarily trapping the hydraulic fluid in the rearward piston chamber 76 to the rear of the valve member. The significance of this delay in the retraction of the valve member 67 will be subsequently explained.

As also illustrated in FIG. 4, the hydraulic fluid in the low-pressure section 151 of the set line 119 will also be directed by way of a branch hydraulic line 164 to the actuating cylinder 104 of the pressure-reduction means 102. This will, of course, result in the displacement piston 106 being elevated in relation to the body 103 as the hydraulic fluid above the actuating piston 105 is returned to the retract" line 120 by way ofa branch hydraulic conduit 165. As previously mentioned, elevation of the displacement piston 106 in the reduced chamber 107 will be effective for significantly decreasing the pressure initially existing in the isolated portions of the branch line 101 and the flow line 81 between the still-closed flow-line control valve 85 and the stillclosed chamber control valves 86 and 87 (not shown in FIG. 4). The purpose of this pressure reduction will be subsequently explained.

Once the wall-engaging member 50, the sealing pad 53 and the fluid-admitting member 57 have respectively reached their extended positions as illustrated in FIG. 4, it will be appreciated tht the hydraulic pressure delivered by the pump 110 will again rise as shown by the curve 158 in FIG. 3. Then, once the pressure in the output line 113 has reached the second level of operating pressure (as represented at B in FIG. 3), the control valve 129 will open in response to this increased pressure level to now discharge the hydraulic fluid previously trapped in the piston chamber 76 to the rear of the valve member 67 back to the reservoir 112.

As illustrated in FIG. 5, once the control valve 129 opens, the hydraulic fluid will be displaced from the rearward piston chamber 76 by way of branch hydraulic lines 166 and 167 to the retract" line as pressured hydraulic fluid from the set line 119 enters the piston chamber 77 ahead of the enlarged-diameter portion 72 of the valve member 67. This will, of course, cooperate to shift the valve member 67 rearwardly in relation to the fluid-admitting member 57 for establishing fluid or pressure communication between the isolated portion of the earth formation 22 and the flow passages 69 and 71 in the valve member by way of the filter screen 80.

Although this is not illustrated in FIG. 5, it will be recalled frorn FIGS. 2A and 28 that the control valves 85-87 are initially closed to isolate the lower portion of the flow line 81 between these valves as well as the branch line 101 leading to the pressure-reduction means 102. However, the flow-line pressure-equalizing control valve 88 will still be open at the time the control valve 129 opens to retract the valve member 67 as depicted in FIG. 5. Thus, as the valve member 67 progressively uncovers the filtering screen 80, well bore fluids at a pressure greater than that of any connate fluids which may be present in the isolated earth formation 22 will be introduced (as shown by the arrow 168) into the upper portion of the flow line 81 and, by way of the flexible conduit member 82, into the rearward end of the tubular member 70. As these high-pressure well bore fluids pass into the annular space 78 around the filtering screen 80, they will be forcibly discharged (as shown by the arrows 169) from the forward end of the fluid-admitting member 57 for washing away any plugging materials such as mudcake or the like which may have become deposited on the internal surface of the filtering screen when the valve member 67 first uncovers the screen. Thus, the control system 25 is operative for providing a momentary flow of well bore fluids for cleansing the filtering screen 80 of unwanted debris or the like before a sampling or testing operation is commenced.

Referring again to FIG. 3, it will be appreciated that once the several components of the formation-testing tool 20 and the control system 25 have reached their respective positions as depicted in FIG. 5, the hydraulic pressure in the output line 113 will quickly increase from the operating level 3" to the operating level C." Once the pump 110 has increased the hydraulic pressure in the output line 113 to the predetermined level C," the control valve 128 will selectively open as depicted in FIG. 6A. As seen there, opening of the control valve 128 will be effective for now supplying hydraulic fluid to the high-pressure section 154 of the set line 119 and two branch conduits 170 and 171 connected thereto for successively closing the control valve 88 and then opening the control valve 85.

In this manner, as depicted by the several arrows at 172 and 173, hydraulic fluid at a pressure representative of the operating level C will be supplied by way of a typical check valve 174 to the upper portion of the piston cylinder 175 of the normally-open control valve 88 as fluid is exhausted from the lower portion thereof by way of a conduit 176 coupled to the retract line 120. This will, of course, be effective for closing the valve member 100 so as to now block further communication between the flow line 81 and the well bore fluids exterior of the tool 20. Simultaneously, the hydraulic fluid will also be admitted into the lower portion of the piston cylinder 91 of the control valve 85. By arranging the biasing spring .99 for the normally-open control valve 88 to be somewhat weaker than the biasing spring 93 for the normally-closed control valve 85, the second valve will be momentarily retained in its closed position until the first valve has had time to close. Thus, once the valve 88 closes, as the hydraulic fluid enters the lower portion of the piston cylinder 91 of the control valve 85, the valve member 94 will be opened as hydraulic fluid is exhausted from the upper portion of the cylinder through a typical check valve 177 and a branch return line 178 coupled to the retract line 120.

It will be appreciated, therefore, that with the tool 20 in the position depicted in FIG. 6A, the flow line 81 is now isolated from the well bore fluids and is in communication with the isolated portion of the earth formation 22 by way of the flexible conduit 82. It will also be recalled from the preceding discussion of FIG. 4 that the branch flow line 101 as well as the portion of the main flow line 81 between the flow-line control valve 85 and the sample chamber control valves 86 and 87 were previously expanded by the upward movement of the displacement piston 106 in the reduced-volume chamber 107. Thus, upon opening of the flow-line control valve 85, the isolated portion of the earth formation 22 will be rapidly communicated with the reducedpressure space temporarily represented by the previously-isolated portions of the flow line 81 and the branch conduit 101.

Accordingly, should there by any producible connate fluids in the isolated earth formation 22, the formation pressure will be effective for displacing these connate fluids by way of the fluid-admitting means 30 into the flow line until such time that the previously-isolated lower portion of the flow line 81 and the branch conduit 101 are filled and pressure equilibrium is again established in the entire flow line. By arranging a typical pressure-measuring transducer, as at 179 (or, if desired, one or more other suitable measuring transducers) in the flow line 81, one or more measurements representative of the characteristics of the connate fluids and the formation 22 may be transmitted to the surface by a conductor 180 and, if desired, recorded on the recording apparatus 26 (FIG. 1). The pressure measurements provided by the transducer 179 will, of course, permit the operator at the surface to readily determine the formation pressure as well as to obtain one or more indications representative of the potential producing ability of the formation 22. The various techniques for analyzing formation pressures are well known in the art and are, therefore, of no significance to understanding the present invention.

Of equal importance, those skilled in the art will also appreciate that the operator can also use the measurements provided by the pressure transducer 179 to reliably determine whether the sealing pad 53 has, in fact, established complete sealing engagement with the earth formation 22 so as to prevent well bore fluids from entering the forward end of the fluid-admitting member 57. The failure of the sealing pad 53 to com pletely effect sealing engagement with the wall of the borehole 21 will, of course, be readily recognized inasmuch as the formation pressures expected to be present in the earth formation 22 will be recognizably lower than the hydrostatic pressure of the well bore fluids at the particular depth which the tool 20 is then situated. This ability to determine the effectiveness of the sealing engagement will, as will subsequently be explained, allow the operator to immediately retract the wallengaging member 50 and the sealing pad 53 without having to unwittingly or needlessly continue the remainder of the complete operating sequence.

Assuming, however, that the pressure measurements provided by the pressure transducer 179 show that the sealing pad 53 is firmly seated, the operator may leave the formation-testing tool 20 in the position shown in FIGS. 6A and 68 as long as it is desired to observe as well as record the pressure measurements. As a result, the operator can determine such things as the time required for the formation pressure to reach equilibrium as well as the rate of pressure increase and thereby obtain valuable information indicative of various characteristics of the earth formation 22 such as permeability and porosity. Moreover, with the new and improved tool 20 of the present invention, the operator can readily determine if collection of a fluid sample is warranted.

It should be particularly noted in FIG. 6B that since the fonnation 22 is relatively unconsolidated, the rearward movement of the valve member 67 in cooperation with the forward movement of the fluid-admitting member 57 will allow only those loose formation materials displaced by the advancement of the fluidadmitting member into the formation to enter the fluidadmitting member. This is to say, the fluid-admitting member 57 can advance into the formation 22 only by displacing loose formation materials; and, since the space opened by the rearward displacement of the valve member 67 is the only available place into which these loose formation materials can enter, further erosion of the formation materials will be halted once the fluid-admitting member has been filled with loose materials. On the other hand, should a formation interval which is being tested be relatively well-compacted, the advancement of the fluid-admitting member 57 will be relatively slight with its nose making little or no penetration into the isolated earth formation. It will, of course, be appreciated that the nose of the fluidadmitting member 57 will be urged outwardly with sufficient force to at least penetrate the mudcake which typically lines'the borehole walls adjacent to permeable earth formations. In this situation, however, the forward movement of the fluid-admitting member 57 will be unrelated to the rearward movement of the valve member 67 as it uncovers the filtering screen 80. In either case, the sudden opening of the valve 85 will cause mudcake to be pulled to the rear of the screen to leave it clear for the subsequent passage of connate fluids.

Referring again to FIG. 3, it will be appreciated that once the several components of the tool 20 and the control system 25 have moved to their respective positions shown in FIGS. 6A and 6B, the hydraulic pressure will again rise until such time that the set line pressure switch 124 operates to halt the hydraulic pump 110. Inasmuch as the pressure switch 124 has a selected operating range (as at 181) with its lower limit preferably being no lower than the operating pressure level C, it will be seen that in the typical situation the pump 110 will be halted shortly after the control valve 88 closes and the control valve opens. At this point in the operating cycle of the formation-testing tool 20,

once a sufficient number of pressure measurements have been obtained, a decision can be made whether it is advisable to obtain one or more samples of the producible connate fluids in the earth formation 22. lf such samples are not desired, the operator can simply operate the switches 33 and 34 for retracting the wallengaging member 50 and the sealing pad 53 without further ado.

On the other hand, should a fluid sample be desired, the control switches 33 and 34 (FIG. 1) are advanced to the next or so-called sample" position 38 to open, for example, a solenoid valve 182 for admitting pressured hydraulic fluid from the high-pressure section 154 of the set" line 119 into the lower portion of the piston cylinder 183 of the sample chamber control valve 86. As depicted in FIG. 7, this will be effective for opening the control valve 86 to admit connate fluids as shown by the arrows 184 through the flow line 81 and the branch conduit 83 into the sample chamber 31. If desired, a chamber selection switch 185 in the surface portion of the system 25 could also be moved from its first sample" position 186 to its so-called second sample" position 187 (H6. 1) to energize a solenoid valve 188 for opening the control valve 87 to also admit connate fluids into the other sample chamber 32. In either case, one or more samples of the connate fluids which are present in the isolated portion of the earth formation 22 can be selectively obtained by the new and improved tool 20. It should be noted that if the formation-testing tool is to be repositioned in the borehole 21 for obtaining pressure measurements from a different formation, as at 23, the unique control system 25 will allow the operator to reserve the sample chamber 32 for a sample from this formation.

As previously mentioned, the new and improved control system 25 functions in such a manner that the hydraulic pump 110 is not operating for any great length of time. As shown in FIG. 3, the pump 110 rapidly reaches its maximum operating pressure as determined by the settings of the pressure switch 124. The pump 110 is then halted and will quite possibly remain halted until it is desired to close-off the sample chambers 31 and 32 and retract the wall-engaging member 50 and the sealing member 53. At this time, the motor 111 will again be started upon moving of the control switches 33 and 34 to their so-called sample-trapping positions 39 so as to restart the pump 110. As previously mentioned, the control valves 122 and 127 momentarily open to enable the pump 110 to reach operating speed and are then reclosed. l-lereagain, the check valve 123 will function to prevent reverse flow of the pressured hydraulic fluid which is then contained in the set line 119. Once the pump 1 10 has reached operating speed, it will commence to operate much in the same manner as previously described with reference to FIG. 3. Thus, as best seen in FIG. 8, the hydraulic pressure in the output line 113 will again begin rising as shown by the curve 189 with momentary halts at various operating levels respectively designated as W"-Z which respectively correspond to the various operating positions of the tool as successively depicted in FIGS. 9-11.

Accordingly, as best seen in FIG. 9, when the control switches 33 and 34 have been placed in their sample trapping" positions 39, the solenoid valve 122 will open to admit hydraulic fluid into the retract" line 120. By means of the electrical conductor 41, however, the

pressure switch 125 is enabled and the pressure switch 126 is disabled so that in this position of the control switches 33 and 34 the maximum operating pressure which the pump can initially reach is limited to the pressure at the operating pressure level W as determined by the pressure switch 125. Thus, by arranging the control valve 131 to open in response to a hydraulic pressure corresponding to the predetermined pressure of the operating level W, hydraulic fluid in the highpressure section 154 of the set line 119 will be returned to the reservoir 112 by means of the return line 117. As the hydraulic fluid in the high-pressure section 154 returns to the reservoir 112, the pressure in this portion of the set line 119 will be rapidly decreased to close the control valve 128 once the pressure in the line is insufficient to hold the valve open. Once the control valve 128 closes, the pressure remaining in the lowpressure section 151 of the set" line 119 will remain at a reduced pressure which is nevertheless effective for retaining the wall-engaging member 50 and the sealing pad 53 fully extended.

As the hydraulic fluid is discharged from the lower portion of the piston cylinder 183 by way of the stillopen solenoid valve 182 and fluid from the retract" line enters the upper portion of the cylinder by way of a branch line 190, the chamber control valve 86 will close to trap the sample of connate fluids which is then present in the sample chamber 31. Similarly, should there also be a fluid sample in the other sample chamber 32, the control valve 87 can also be readily closed by operating the switch 185 to reopen the solenoid valve 188. Closure of the control valve 86 (as well as the valve 87) will, of course, be effective for trapping fluid samples in one or the other or both of the sample chambers 31 and 32.

Once the control valve 86 (and, if necessary, the control valve 87) has been reclosed, the control switches 33 and 34 are moved to their next or so-called retract" switching positions 40 for initiating the simultaneous retraction of the well-engaging member 50 and the sealing pad 53. In this final position of the control switches 33 and 34, the pressure switch is again rendered inoperative and the pressure switch 126 is enabled so as to now permit the hydraulic pump 110 to be operated at rated capacity for attaining hydraulic pressures greater than the operating level W." Thus, as depicted in FIG. 8, once the pressure switch 125 has again been disabled, the pressure switch 126 will now function to operate the pump 110 so that the pressure will now quickly rise until it reaches the operating level kix'ii At this point, as shown in FIG. 10, hydraulic fluid at the pressure level X will be supplied as shown by the arrows 191 through the retract line 120 and the branch hydraulic line 176 for reopening the pressureequalizing control valve 88 to admit well bore fluids into the flow line 81 as shown by the arrows 192. Opening of the pressure-equalizing valve 88 will admit well bore fluids into the isolated space defined by the sealing pad 53 so as to equalize the pressure differential existing across the pad. Hydraulic fluid displaced from the upper portion of the piston chamber of the control valve 88 will be discharged through a typical relief valve 193 which is arranged to open only in response to pressures equal or greater than that of the operating level X. The hydraulic fluid displaced from the piston chamber 175 through a relief valve 193 will be returned to the reservoir 112 by way of the branch hydraulic line 170, the high-pressure section 154 of the set line 119, the still-open control valve 131 and the return line 117.

Turning now to FIG. 11, the situation illustrated there is representative of the operation of the formation-testing tool 20 when the hydraulic pressure in the output line 113 has either reached the operating level Y or, if desired, a higher level as at Z" (FIG. 8). At this point, pressured hydraulic fluid in the retract line 120 will reopen the control valve 130 to communicate the low-pressure section 151 of the set line 119 with the reservoir 112. When this occurs, hydraulic fluid in the retract line will be admitted to the retract side of the several piston actuators, 51, 52, 55 and 56 as shown by the arrows at 195. Similarly, the pressured hydraulic fluid will also be admitted into the annular space 66 in front of the enlarged-diameter piston portion 64 for retracting the fluid-admitting member 57 as well as into the annular space 76 for returning the valve member 67 to its forward position. The hydraulic fluid exhausted from the several piston actuators 51, 52, 55 and 56 as well as the piston chambers 65 and 77 will be returned directly to the reservoir 112 by way of the high-pressure section 151 of the set line 119 and the control valve 130. This action will, of course, retract the wall-engaging member 50 as well as the sealing pad 53 against the tool body 28 to permit the tool 20 to be either repositioned in the well bore 21 or returned to the surface if no further testing is desired.

Referring again to FIG. 10, it will be noted that although there is an operating pressure applied to the upper portion of the piston cylinder 91 for the flow-line control valve 85 at the time that the control valve 88 is reopened, a normally-closed relief valve 194 which is paralleled with the check valve 177 is held in a closed position until the increasing hydraulic pressure developed by the pump 110 exceeds the operating level (Y to Z) used to retract the wall-engaging member 50 and the sealing pad 53. At this point in the operating sequence of the new and improved tool 20, the flow-line control valve 85 will be reclosed (not shown in FIG. 11).

The pump 110 will, of course, continue to operate until such time that the hydraulic pressure in the output line 113 reaches the upper limit determined by the setting of the pressure switch 126. At some convenient time thereafter, the control switches 33 and 34 are again returned to their initial or Off positions 35 for halting further operation of the pump motor 111 as well as reopening the solenoid valve 127 to again communicate the retract line 120 with the fluid reservoir 112. This completes the preferred operating cycle of the new and improved formation-testing tool 20.

It will be appreciated, therefore, that the new and improved testing tool 20 is capable of performing one or more testing or sampling operations as may be required without having to remove the tool from the borehole 21 between each operation. Moreover, of equal importance, it will be recognized that the versatility of the new and improved control system will enable the operator to monitor the performance of the tool 20 during the course of a given testing or sampling operation so that either changes can be made as required to properly respond to various downhole conditions or else the operation can be terminated without further loss of time should this be deemed necessary. Those skilled in the art will, of course, recognize the significance of this flexibility.

Although the usual situation will be that the new and improved tool 20 will be operated as previously'described in detail for obtaining a series of pressure measurements and one or two fluid samples, it is not at all uncommon for unexpected or unwanted conditions to occur which will hamper or prevent the successful completion of that particular testing or sampling operation. For example, as previously mentioned, it is quite often found that the sealing pad 53 has, for one reason or another, failed to effect complete sealing with the wall of the borehole 21. Obviously, this condition will absolutely preclude the securing of either formation pressure measurements or representative fluid samples since borehole fluids will simply enter the fluidadmitting means 30 should the testing or sampling operation be continued.

This condition will, of course, be readily apparent since the flow line 81 is initially filled with well bore fluids (FIGS. 2A-2B and 4)-and this will cause the pressure transducer 179 to indicate the hydrostatic pressure of the well bore fluids. When the control switches 33 and 34 are advanced to their third positions 37 to set the tool 20 and the output pressure of the pump 113 reaches the pressure level B," the control valve 129 will function to open the fluid-admitting means 30 as the valve member 67 moves rearwardly to place the formation, as at 22, in communication with the flow line 81 (FIG. 5). Then, as shown in FIG. 6A, once the pump 113 reaches the pressure level C, the equalizing valve 88 will close and the flow-line control valve will then open to rapidly communicate the remaining or reduced-pressure portion of the flow line 81 with the fluid-admitting means 30. When this occurs, only one of three things can be considered. First of all, if there is a substantial drop in the pressure reading provided by the surface devices 26 followed by an increase in pressure to a level characteristic of typical formation pressures, it can be concluded that the sealing pad 53 is sealingly engaged with the wall of the borehole 21 and that the formation, as at 22, is permeable so as to warrant the continuance of the testing or sampling operation as previously described to determine the nature of the formation and whatever connate fluids may be present therein.

On the other hand, if the pressure in the flow line 81 fails to drop and instead remains at the same level, it will be known that the sealing pad 53 is not tightly sealed with the wall of the borehole 21 and that well bore fluids are entering the nose of the fluid-admitting member 57. Alternatively, if the pressure in the flow line 81 drops but fails either to rise at all or to increase at a reasonable rate, it can be safely concluded either that the formation under investigation is not productive or else that the fluidadmitting means 30 were somehow plugged despite the flushing action depicted in FIG. 5. Either situation, of course, makes it futile to continue further with the testing or sampling operation. Thus, in keeping with the objects of the present invention, the control switches 33 and 34 are simply skipped over the positions 38 and 39 and advanced directly to their switching positions at 40 without further ado. As

shown in FIGS. 10 and 11, this will, of course, return the tool 20 to its initial position (FIGS. 2A and 2B) so that one or more attempts can be made after moving 

1. Formation-testing apparatus adapted for suspension in a well bore traversing earth formations and comprising: a body having a fluid passage adapted to receive connate fluids; fluid-admitting means on said body and adapted to be selectively engaged with a well bore wall for isolating a portion thereof from well bore fluids; first pressure-responsive means on said body and operable in response to a first operating pressure of a selected magnitude for moving said fluid-admitting means against a well bore wall to establish communication with earth formations therebeyond; second pressure-responsive means on said body and operable in response to a second operating pressure of a selected different magnitude for communicating said fluid passage with said fluidadmitting means; and means on said body coupled to said first and second pressureresponsive means and selectively operable for successively developing at least said first and second operating pressures in turn to operate said first and second pressure-responsive means in a predetermined sequence.
 2. The formation-testing apparatus of claim 1 wherein said second operating pressure is greater than said first operating pressure.
 3. The formation-testing apparatus of claim 1 further including transducer means on said body and in communication with said fluid passage for measuring at least one characteristic of connate fluids.
 4. The formation-testing apparatus of claim 3 wherein said transducer means include a pressure-measuring transducer.
 5. The formation-testing apparatus of claim 1 further including: means on said body defining a fluid-receiving chamber; and third pressure-responsive means coupled to said motive means and operable in response to a third operating pressure of a selected magnitude developed by said motive means and different than said first and second operating pressures for communicating said fluid passage with said fluid-receiving chamber.
 6. The formation-testing apparatus of claim 5 wherein said second operating pressure is greater than said first operating pressure, and said third operating pressure is greater than said second operating pressure.
 7. The formation-testing apparatus of claim 5 further including transducer means on said body and in communication with said fluid passage for measuring at least one characteristic of connate fluids entering said fluid passage and said fluid-receiving chamber.
 8. The formation-testing apparatus of claim 7 wherein said transducer means include a pressure-measuring transducer.
 9. Formation-testing apparatus adapted for suspension in a well bore traversing earth formations and comprising: a body having a fluid passage adapted to receive connate fluids; fluid-admitting means on said body and adapted to be selectively engaged with a well bore wall for isolating a portion thereof from well bore fluids; actuating means on said body and adapted for supplying an actuating fluid at a range of varying output pressures; first pressure-responsive means on said body operable in response to a first predetermined pressure for selectively placing said fluid-admitting means against a well bore wall to establish communication with earth formations therebeyond and operable in response to a fourth predetermined pressure for selectively displacing said fluid-admitting means from a well bore wall to discontinue such communication; second pressure-responsive means on said body operable in response to a second predetermined pressure for selectively communicating said fluid-admitting means with said fluid passage and operable in response to a third predetermined pressure for selectively discontinuing communication between said fluid-admitting means and said fluid passage; and control means selectively operable from the surface for communicating an actuating fluid from said actuating means wiTh each of said pressure-responsive means to sequentially place said fluid-admitting means against a well bore wall, communicate and then discontinue communication between said fluid-admitting means and said fluid passage, and finally displace said fluid-admitting means from a well bore wall in response to successive changes of said output pressures of said actuating means to each of said predetermined pressures in turn.
 10. The formation-testing apparatus of claim 9 wherein said fourth predetermined pressure is greater than said first predetermined pressure.
 11. The formation-testing apparatus of claim 9 wherein said third predetermined pressure is greater than said second predetermined pressure.
 12. The formation-testing apparatus of claim 9 wherein said fourth and third predetermined pressures are respectively greater than said first and second predetermined pressures.
 13. The formation-testing apparatus of claim 9 further including: sample-collecting means on said body and adapted for receiving a sample of connate fluids in said fluid passage; and third pressure-responsive means on said body operable in response to a fifth predetermined operating pressure for communicating said fluid passage with said sample-collecting means as said control means communicate an actuating fluid with said third pressure-responsive means and operable in response to a sixth predetermined operating pressure for discontinuing communication between said fluid passage and said sample-collecting means as said control means communicate an actuating fluid with said third pressure-responsive means.
 14. The formation-testing apparatus of claim 13 wherein said control means further include: valve means on said body and selectively operable from the surface for controlling fluid communication between said third pressure-responsive means and said actuating means.
 15. The formation-testing apparatus of claim 13 wherein said fifth predetermined pressure is greater than said fourth predetermined pressure and said fourth predetermined pressure is greater than said first predetermined pressure.
 16. The formation-testing apparatus of claim 15 wherein said third predetermined pressure is greater than said second predetermined pressure and said second predetermined pressure is greater than said sixth predetermined pressure.
 17. The formation-testing apparatus of claim 9 further including: pressure-measuring means cooperatively associated with said fluid passage and adapted for providing signals at the surface representative of pressures of fluids in said fluid passage.
 18. The formation-testing apparatus of claim 9 wherein said first pressure-responsive means include: piston-actuator means on said body and including at least one piston member adapted for extension from said body upon application of said first predetermined pressure to said piston-actuator means and adapted for retraction away from a well bore wall upon application of said fourth predetermined pressure to said piston-actuator means.
 19. The formation-testing apparatus of claim 18 further including: wall-engaging means coupled to said piston member and adapted for movement thereby into anchoring engagement with a well bore wall upon extension of said piston member from said body.
 20. The formation-testing apparatus of claim 18 further including: means cooperatively coupling said fluid-admitting means to said piston member for movement thereby into engagement with a well bore wall upon extension of said piston member from said body.
 21. The formation-testing apparatus of claim 9 wherein said first pressure-responsive means include: piston-actuator means on said body and including at least first and second piston members respectively adapted for extension in opposite directions from said body upon application of said first predetermined pressure to said piston-actuator means and respectively adapted for retraction back to said body upon application of said fourth preDetermined pressure to said piston-actuator means; wall-engaging means coupled to said first piston member and adapted for movement thereby into and out of anchoring engagement with a well bore wall upon extension and retraction of said first piston member; and means cooperatively coupling said fluid-admitting means to said second piston member for movement thereby into and out of engagement with a well bore wall upon extension and retraction of said second piston member.
 22. The formation-testing apparatus of claim 21 further including: wall-sealing means cooperatively arranged on said fluid-admitting means and adapted for sealing engagement with a well bore wall upon extension of said second piston member.
 23. Formation-testing apparatus adapted for suspension in a well bore traversing earth formations and comprising: a body having a fluid passage arranged thereon for receiving connate fluids; fluid-admitting means coupled to said fluid passage and cooperatively arranged on said body for engagement with a well bore wall to isolate a portion thereof from well bore fluids; first pressure-responsive means adapted for selectively engaging and disengaging said fluid-admitting means with and from a well bore wall and including first piston means operatively arranged for extension toward a well bore wall in response to a pressure differential acting on one end of said first piston means and for retraction from a well bore wall in response to a pressure differential acting on the other end of said first piston means; second pressure-responsive means adapted for selectively controlling the flow of fluids in said fluid passage and including valve means movable between open and closed operating positions and coupled to said fluid passage, and second piston means connected to said valve means and operatively arranged for selectively moving said valve means to one of said operating positions in response to a pressure differential acting on one end of said second piston means and for selectively moving said valve means to the other of said operating positions in response to a pressure differential acting on the other end of said second piston means; hydraulic actuating means on said body and including a pump selectively operable from the surface and adapted for supplying a hydraulic fluid at progressively-increasing pressures over a selected range of operating pressures, a first hydraulic conduit coupled to said one end of said first piston means, a second hydraulic conduit coupled to said other end of said first piston means and to said other end of said second piston means, and a third hydraulic conduit coupled to said one end of said second piston means; first control means operable upon a first operating cycle of said pump for selectively coupling said first hydraulic conduit to the outlet of said pump and coupling said second hydraulic conduit to the inlet of said pump to extend said first piston means as said pump first supplies a hydraulic fluid at a first selected pressure level to said first hydraulic conduit; second control means operable only upon a further increase in fluid pressure in said first hydraulic conduit above said first selected pressure level for coupling said first hydraulic conduit to said third hydraulic conduit to supply hydraulic fluid to said one end of said second piston means only so long as the fluid pressure in said first hydraulic conduit is no less than said first selected pressure level; third control means operable upon a second operating cycle of said pump for selectively coupling said second hydraulic conduit to said pump outlet and coupling said third hydraulic conduit to said pump inlut to supply hydraulic fluid at a second selected pressure level to said other end of said second piston means; and fourth control means operable only upon a further increase in fluid pressure in said second hydraulic conduit above said second selected pressure level for coupling said first hydraulic conduit to said pump inlet only so long as the fluid pressure in said second hydraulic conduit is no less than said second selected pressure level.
 24. The formation-testing apparatus of claim 23 wherein said one operating position of said valve means is said open position of said valve means.
 25. The formation-testing apparatus of claim 23 wherein said one operating position of said valve means is said closed position of said valve means.
 26. The formation-testing apparatus of claim 23 further including: control means selectively operable from the surface for controlling the admission of hydraulic fluid from said third hydraulic conduit to said one end of said second piston means.
 27. The formation-testing apparatus of claim 23 further including: means cooperatively coupling said fluid-admitting means to said first piston means for moving said fluid-admitting means into and out of engagement with a well bore wall upon extension and retraction of said first piston means.
 28. The formation-testing apparatus of claim 23 further including: sample-collecting means coupled to said fluid passage downstream of said valve means.
 29. The formation-testing apparatus of claim 28 further including: control means selectively operable from the surface for controlling the admission of hydraulic fluid from said third hydraulic conduit to said one end of said second piston means.
 30. Formation-testing apparatus adapted for suspension in a well bore traversing earth formations and comprising: a body having a fluid passage arranged thereon for receiving connate fluids; fluid-admitting means coupled to said fluid passage and cooperatively arranged on said body for engagement with a well bore wall to isolate a portion thereof from well bore fluids; first pressure-responsive means adapted for selectively engaging and disengaging said fluid-admitting means with and from a well bore wall and including first piston means operatively arranged for extension toward a well bore wall in response to a pressure differential acting on one end of said first piston means and for retraction from a well bore wall in response to a pressure differential acting on the other end of said first piston means; second pressure-responsive means adapted for selectively controlling the flow of fluids in said fluid passage and including valve means movable between open and closed operating positions and coupled to said fluid passage, and second piston means connected to said valve means and operatively arranged for selectively moving said valve means to one of said operating positions in response to a pressure differential acting on one end of said second piston means and for selectively moving said valve means to the other of said operating positions in response to a pressure differential acting on the other end of said second piston means; hydraulic actuating means on said body and including a pump selectively operable from the surface and adapted for supplying a hydraulic fluid at progressively-increasing pressures over a selected range of operating pressures, a first hydraulic conduit coupled to said one end of said first piston means and to said one end of said second piston means, and a second hydraulic conduit coupled to said other end of said first piston means; first control means operable upon a first operating cycle of said pump for selectively coupling said first hydraulic conduit to the outlet of said pump and coupling said second hydraulic conduit to the inlet of said pump to extend said first piston means as said pump first supplies a hydraulic fluid at a first selected pressure level to said first hydraulic conduit; second control means operable only upon a further increase in fluid pressure in said first hydraulic conduit above said first selected pressure level for coupling said second hydraulic conduit to said other end of said second piston means to receive hydraulic fluid therefrom only so long as the fluid pressure in said firsT hydraulic conduit is no less than said first selected pressure level; third control means operable upon a second operating cyle of said pump for selectively coupling said second hydraulic conduit to said pump outlet to supply hydraulic fluid at a second preselected pressure level to said other end of said second piston means; and fourth control means operable only upon a further increase in fluid pressure in said second hydraulic conduit above said second selected pressure level for coupling said first hydraulic conduit to said pump inlet only so long as the fluid pressure in said second hydraulic conduit is no less than said second selected pressure level.
 31. The formation-testing apparatus of claim 30 further including: means coupling said fluid-admitting means to said first piston means for moving said fluid-admitting means into and out of engagement with a well bore wall upon extension and retraction of said first piston means.
 32. The formation-testing apparatus of claim 30 wherein said fluid-admitting means include: a sealing member cooperatively arranged for sealing engagement with a well bore wall and having a central opening, and a tubular fluid-conducting member coupled to said fluid passage and disposed within said central opening.
 33. The formation-testing apparatus of claim 32 wherein said second pressure-responsive means are cooperatively arranged on said tubular fluid-conducting member for controlling the flow of fluids between said tubular fluid-conducting member and said fluid passage.
 34. The formation-testing apparatus of claim 33 further including: means coupling said fluid-admitting means to said first piston means for moving said fluid-admitting means into and out of engagement with a well bore wall upon extension and retraction of said first piston means.
 35. Formation-testing apparatus adapted for suspension in a well bore traversing earth formations and comprising: a body having a fluid passage arranged thereon for receiving connate fluids; fluid-admitting means coupled to said fluid passage and cooperatively arranged on said body for engagement with a well bore wall to isolate a portion thereof from well bore fluids; first pressure-responsive means adapted for selectively engaging and disengaging said fluid-admitting means with and from a well bore wall and including piston means operatively arranged for extension toward a well bore wall in response to a pressure differential acting on one end of said piston means and for retraction from a well bore wall in response to a pressure differential acting on the other end of said piston means; second pressure-responsive means adapted for selectively controlling the flow of fluids in said fluid passage and including first valve means coupled to said fluid passage and movable between an open position to admit well bore fluids into said fluid passage and a closed position to block the entrance of well bore fluids into said fluid passage, first piston-actuator means connected to said first valve means and operatively arranged for selectively moving said first valve means to its said closed position in response to a pressure differential acting on one end of said first piston-actuator means and for selectively moving said first valve means to its said open position in response to a pressure differential acting on the other end of said first piston-actuator means, second valve means connected in said fluid passage and movable between a closed position to block the flow of fluids through said fluid passage and an open position to allow fluids to flow through said fluid passage, and second piston-actuator means connected to said second valve means and operatively arranged for selectively moving said second valve means to its said open position in response to a pressure differential acting on one end of said second piston-actuator means and for selectively moving said second valve means to its said closed position in response to a pressure differential acting on the other end of said second piston-actuator means; hydraulic actuating means on said body and including a pump selectively operable from the surface and adapted for supplying a hydraulic fluid at progressively-increasing pressures over a selected range of operating pressures, a first hydraulic conduit coupled to said one end of said piston means, a second hydraulic conduit coupled to said other end of said piston means and to said other ends of said first and second piston-actuator means, and a third hydraulic conduit coupled to said one ends of said first and second piston-actuator means; first control means operable upon a first operating cycle of said pump for selectively coupling said first hydraulic conduit to the outlet of said pump and coupling said second hydraulic conduit to the inlet of said pump to extend said piston means as said pump first supplies a hydraulic fluid at a first selected pressure level to said first hydraulic conduit; second control means operable only upon a further increase in fluid pressure in said first hydraulic conduit above said first selected pressure level for coupling said first hydraulic conduit to said third hydraulic conduit to supply hydraulic fluid to said ends of said first and second piston-actuator means only so long as the fluid pressure in said first hydraulic conduit is no less than said first selected pressure level; third control means operable upon a second operating cycle of said pump for selectively coupling said second hydraulic conduit to said pump outlet and coupling said third hydraulic conduit to said third hydraulic conduit to said pump inlet to supply hydraulic fluid at a second selected pressure level to said other ends of said first and second piston-actuator means; and fourth control means operable only upon a further increase in fluid pressure in said second hydraulic conduit above said second selected pressure level for coupling said first hydraulic conduit to said pump inlet only so long as the fluid pressure in said second hydraulic conduit is no less than said second selected pressure level.
 36. The formation-testing apparatus of claim 35 wherein said piston means include a laterally-extendible piston member adapted for extension and retraction relative to one side of said body, and said fluid-admitting means are mounted on the other side of said body for engagement with one well bore wall upon extension of said extendible piston member against the opposite well bore wall.
 37. The formation-testing apparatus of claim 35 wherein said piston means include a laterally-extendible piston member adapted for extension and retraction relative to one side of said body, and further including: means cooperatively coupling said fluid-admitting means to said piston member for moving said fluid-admitting means into and out of engagement with a well bore wall upon extension and retraction of said piston member.
 38. The formation-testing apparatus of claim 35 wherein said piston means include first and second laterally-extendible piston members respectively adapted for simultaneous extension and retraction relative to opposite sides of said body, and further including: means cooperatively coupling said fluid-admitting means to said first piston member for moving said fluid-admitting means into and out of engagement with a well bore wall upon extension of said first and second piston members.
 39. The formation-testing apparatus of claim 35 further including: sample-collecting means coupled to said fluid passage downstream of said second valve means.
 40. The formation-testing apparatus of claim 39 further including: fifth control means selectively operable from the surface for controlling the admission of hydraulic fluid from said third hydraulic conduit to said one end of said second piston-actuator means. 